Assembly device



Aug. 6, 1968 F. J. CALLAHAN, JR 3,395,457

ASSEMBLY DEVICE Original Filed July 13, 1964 2 Sheets-Sheet l FIG. 3

INVENTOR. 38 FRANCIS J. CALLAHAN, JR.

ATTORNEY$ Aug. 6, 1968 F. J CALLAHAN. JR 3,395,457

ASSEMBLY DEVICE Original Filed July 15, 1964 2 Sheets-Sheet 2 FIG. 5

INVENTOR FRANCIS J. CALLAHAN, JR.

ATTORNEYS United States Patent 2 Claims. (Cl. 33-174) This applicationis a division of application Ser. No. 382,132, filed July 13, 1964, nowPatent No. 3,255,521.

This invention relates to a method of assembling a tube and a fitting.More specifically, the invention relates to a method of assembling atube to a fitting of the type that is sealingly engaged upon the tube bymeans of swaging.

A fitting of the type referred to, which is secured to the tube by meansof a swaging action, generally comprises a coupling body member whichcontains one or more tapered ferrules and a coupling nut in threadedengagement with the coupling body. As the coupling nut is advanced onthe coupling body, the ferrules are subjected to axial pressure and areforced into a tapered mouth in the coupling body thereby causing them tocontract upon the tubing. The coaction of the coupling nut and theferrules, as will be discussed in more detail hereinafter, causes radialcontraction of the ferrules to create a clinching grip on the tube bymeans of the swaging action of the ferrules thereupon. Since thecontraction of the ferrules upon the tube is produced by an advancementof the coupling nut along the coupling body, it will be apparent thatthe amount of contraction of the ferrules is determined by the amount ofadvancement of the coupling nut.

In making an effective and tight connection between a tube and this typeof fitting, it is important that the dimensional relationships betweenthe tube itself and the various components of the fitting, do not varyappreciably from those prescribed. Deviations from the prescribedtolerances for any of the components may sometimes result inunsatisfactory connections.

In its broadest sense, the invention relates to a method of assembling atube and a fitting of the aforementioned type wherein the dimensionalcharacteristics of the tube must be correlated with those of the fittingto produce an efiective connection. More specifically, the inventionrelates to a method of assembling this type of fitting to a tube in amanner which will produce a more or less constant amount of swaging ortube deformation, notwithstanding significant variations, withintolerances, of tube dimensions.

The novel method, according to the principles of the invention,generally is adapted for use in connection with a fitting of the generaltype wherein a coupling nut is advanced on the coupling body, thereby tocontract one or more ferrules contained in the coupling body intogripping relation with the tube wall. An example of such a fitting isdisclosed in US. Patent No. 3,103,373, issued Sept. 10, 1963 to Fred A.Lennon and Emery I. Zahuranec, and assigned to the same assignee as thepresent application.

The invention disclosed and claimed in the aforementioned patentincludes an embodiment in which the pitch of the threads interconnectingthe coupling body and the coupling nut was predetermined and selected sothat one and one-quarter turns of the coupling nut from the fingertightcondition was required to deform the ferrules radially inwardly againstthe tube wall in an amount sufiicient to obtain optimum gripping andsealing for low to intermediate pressures. One and one-half turns fromthe finger-tight condition proved particularly effective for pressuresof somewhat higher order of magnitude.

These fittings generally comprise a threaded body portion having a fiuidpassage therethrough, adapted to receive a generally cylindricalelongated member, such as a tube, a thermocouple, or other rodlike malemember. In those instances in which the male member to be gripped is atube or the like, the passage is provided at one end with a coaxialcounterbore having a bottom which forms a radially extending shoulderfor engagement with the tube end. The passage also includes a coaxialtapered month which provides an annular camming surface adapted tocooperate with an annular ferrule.

The generally frustoconical annular ferrule is received by the taperedmouth of the camming surface. A second annular ferrule is received bythe first frustoconical ferrule and is provided at its other extremitywith a radially extending flange. Threadedly received upon the bodymember is a coupling nut, which includes a radially inwardly directedflange which cooperates with the outwardly directed flange of thesecond. ferrule. As the coupling nut is advanced upon the coupling body,it engages the second or back ferrule and forces this against the frontferrule, which, in turn, causes the frustoconical or front ferrule to beforced into the tapered mouth of the coupling body. As the ferrules aredriven forwardly, they move along the inwardly directed camming surfacesand thereby radially contract upon the external surface of thecylindrical member.

To a considerable extent, the successful utilization of couplings of theaforementioned type depends upon controlled constriction or swaging ofthe walls of the tubular member to be coupled. In fittings of this type,the optimum amount of tube wall constriction or swaging isapredetermined quantity. For a coupling of given design, a precise numberof coupling nut turns, or fractions of turns, will be required to obtainthe linear nut advancement necessary to produce the optimum amount ofswaging. The pitch of the threads interconnecting the coupling nut andcoupling body will in turn be determinative of the number of turnsrequired to produce this linear advancement. If the coupling nut isgiven less than the prescribed number of turns, the ferrules will not becontracted or collapsed sufficiently to produce the required swaging ofthe tube wall. The insuificient swaging of the tube wall results in aconnection which is susceptible to leakage. Should the coupling nut beadvanced more than the prescribed amount, the annular ferrules will beovercontracted upon the tube Wall. This excessive swaging may result inreducing the number of times the fitting can be disconnected and remade.

Accordingly, the fittings and the conduits or pipes to be used inconnection therewith must be manufactured in accordance with relativelyclose tolerances, so that a given number of turns on the coupling nutwill contract the ferrules a predetermined amount, thereby to producethe proper swaging of the tube wall.

In general, the problems which have been encountered are due either todeviations from the prescribed tolerances in the manufacture of thetubing. or the failure of the assembler to advance the coupling nut theprescribed amount, or both. Most often, the fitting itself ismanufactured in accordance with the prescribed tolerances but difficultyis usually occasioned by deviations in the tolerances of the tube.

The use of these fittings with extruded members, such as plastic tubes.has been particularly troublesome due to significant variations fromprescribed tolerances inherent from extrusion processes. In theinstances where the outer diameter of the tube is larger thanprescribed, and the coupling nut is rotated to the standard orprescribed amount, an excessive amount of swaging of the tube isproduced. In the event the outer diameter of the tube is smaller thanprescribed and the coupling nut is again rotated the standard amount anadequately swaged connection will result.

In an attempt to alleviate the problems of inadequate or excessiveswaging which are specifically due to the failure of the user to advancethe coupling nut the prescribed number of turns, various types ofgauging means have been devised. These gauges are designed to indicateprecisely the amount of advance of the coupling nut which is required toproduce a secure connection between a properly dimensioned fitting andtube. One of these gauging devices amounts to an annular tighteninglimit member disposed between the coupling nut and a fixed surface onthe body of the coupling. In use, the coupling nut would be rotateduntil its advance is arrested by the annual tightening limit member.

If both the fitting and the conduit are manufactured in accordance withpredetermined tolerances, this method of assembly has been effective ingiving the proper connection. It is significant to note that thistechnique of gauging merely controls the amount of contraction of theferrules by limiting the advance of the coupling nut. An effectiveconnection, however, requires a relatively definite amount of swaging ofthe tube walls and this is dependent upon the size of the tube as wellas the amount of advance of the coupling nut. Accordingly, thistechnique of merely limiting the advance of the coupling nut is notreliable if the tube is larger or smaller than prescribed for theparticular fitting involved.

Another method of assembling fittings of this type involves theinsertion of a no-go gauge between the coupling nut and the body of thecoupling. The coupling nut is then advanced to the no-go position. Thismethod is attendant with the disadvantages noted supra regarding theannular tightening limit means in the event of dimensional variances inthe tube diameter.

In addition to the disadvantages discussed supra, these methods ofassembling cannot be practiced at all on certain types of fittings.

It will be observed that in using either the no-go gauge or thetightening limit means, which in effect is a no-go gauge, a referencesurface must be provided upon the fitting. Certain types of fittings,however, such as Ts and elbows, are not constructed with a referencesurface thereon. Accordingly, these methods have no applicationwhatsoever, where such fittings are involved.

With the foregoing problems in mind, it is an object of this inventionto provide a method of assembling a swage action gripping device to atube in a manner such that the amount of deformation or swaging of thetube wall is not affected by dimensional variations of the tubediameter.

It is a further object of this invention to provide a method ofassembling swage action gripping devices to tubes which assuresuniformly reliable connections without regard to variations between thedimensions of the fitting and the tube.

It is a further object of this invention to provide a method ofassembling swage action gripping devices to tubes wherein the amount ofadvance of the coupling nut is not measured in terms of a precise numberof turns or fractions thereof.

It is a still further object of this invention to provide a method ofassembling a swage action coupling to a tube wherein the amount ofadvance of the coupling nut is not measured in terms of turns but interms of the linear distance the coupling has been advanced on thefitting.

It is a still further object of this invention to provide a method ofassembling fittings of the aforementioned types to tubes or conduits,wherein the necessary amount of constriction or swaging action for aparticular size of conduit is predetermined in terms of the requisitelinear travel of the coupling nut relative to the tube.

Another object of this invention is to provide a method of accuratelycontrolling the required amount of linear travel of the coupling nut onthe body of a swage action fitting which has no reference surfacethereon for cooperation with a gauging means.

A still further object of the invention is to provide a method ofassembling tubes or conduits to couplings of the aforementioned naturewhich includes the step of indicating on the tube or conduit itself theamount of advance of the coupling nut which is necessary to produce aprescribed connection.

Another object of this invention is to provide a number of gaugingdevices adapted to be used in a method of assembling couplings andpipes.

Another object of this invention is to provide a cup type gauging devicewhich includes a generally cylindrical bore having the dimensions ofdepth and diameter thereof correlated with the design characteristics ofa swage action gripping device.

A further object of this invention is to provide a series of cup typegauging devices each adapted for use in connection with correspondingsizes of tubes to indicate thereon the amount which the coupling nut ofa given sized swage action type coupling must be advanced to produce aproper connection with a particular tube.

Another object of the invention is to provide a series of measuringdevices or cap gauges each of which includes a generally cylindricalbore wherein the diameter of the bore and the depth thereof areinterrelated to the pitch of the threads interconnecting the couplingnut to the coupling body and also to the various camming surfaces of thefitting which cooperate to swage the fitting to the tube.

Other and more specific objects of the invention will be apparent fromthe detailed description to follow and from the drawings.

In the drawings:

FIG. 1 is a fragmentary view, partly in longitudinal section, of a swageaction gripping device of the type with which the instant method ofassembly is generally concerned. FIG. 1 also shows the relativepositions of the various components of the swage action gripping devicein the initial stages of assembly of the conduit;

FIG. 2 is a sectional view of a gauge device used in the practice ofthis invention;

FIG. 3 is a sectional view of a gauging device, identical in design tothat illustrated in FIG. 2, but differently dlmensioned, used in thepractice of the instant method;

FIG. 4 is a perspective view of a gauging device, as shown in FIGS. 2and 3, When used in connection with a conduit for marking the pipe orconduit in accordance with the teachings of the invention;

FIG. 5 is a fragmentary view of the conduit shown in FIG. 4 after havingbeen marked in accordance with the principles of the instant invention;

FIG. 6 is a fragmentary view, partly in section, showin gthe completedconnection between the swage type fittlng or coupling device and theconduit in accordance with the principles of the invention; and

FIG. 7 is an alternative embodiment of the invention specificallyadapted to visually indicate whether or not the gauging device isproperly applied to the tube.

Like parts are designated by like reference numerals 1n the severalviews of the drawings.

It is thought that the nature of the invention can be understood moreeasily by first considering certain details of the swaging or grippingtype of fitting or coupling that 1s to be assembled to a tube orconduit. Referring now, more particularly, to the drawings, FIG. 1 showsa typical gripping or swaging action type coupling indicated generallyat 10. The gripping device 10 includes a coupling body 12 which may beprovided intermediate its ends with tool pads 14 or otherwrench-engaging surfaces. Extending longitudinally through the body 12is a substantially cylindrical passageway, designated generally at 16and having a shoulder 17 against which tube 30 abuts.

Body member 12 is externally threaded at 18 to re ceive a coupling nut20 which is internally threaded. The rear face of the coupling nut 20 isdesignated 19. In a typical example, the threads 18 probably would havea pitch of about 20 threads per inch. The body 12 also is provided witha tapered annular mouth 22 to receive a front ferrule 26. A secondferrule, or back ferrule 28, is held in a captive relationship betweenthe front ferrule and an internal annular flange 21 formed on theunthreaded end of the coupling nut 20. Upon relative rotation of thecoupling nut 20 and the coupling body 12, the generally tapered shape ofthe ferrules 26 and 28 cause a sequential inward gripping of the tube 30as explained in detail in the above-mentioned Patent No. 3,103,373.

In a swage type fitting of the nature here involved, the amount ofswaging or deformation of the pipe is very critical since too great adeformation or swaging will cause an internal obstruction in the pipeand create fluid flow problems as well as possibly a rupture of the pipeand assuredly a defective connection. An inadequate amount of swagingwill produce an insecured fitting and allow leakage.

In practice, the various elements of the fitting are manufactured toextremely close tolerances and most are used in connection with tubingwhich is manufactured within very close tolerances. The couplingassembly is shipped to the user in finger-tight relation, and when usedis slipped onto the tubing until the tube abuts against the seat of thecoupling body.

Various ways and means have been used tocontrol very accurately theamount of swaging or gripping between the coupling and the pipe. Onetechnique has been to use a fixed gauge between the forward portion ofthe coupling nut 20 and the sides of the tool pads 14 and to rotate thenut until further advance is arrested by the gauge. Another practice hasbeen to rotate the coupling nut a prescribed amount. When the prescribedtolerances of all the critical elements in the fitting, as well as thedimensions of the pipe are adhered to accurately, the aforementionedmethods of assembly have generally proved adequate. Difficulty arises,however, if the outer diameter of the pipe is not maintained, aspredescribed. In certain grades of commercially available tubing, andparticularly plastic tubing, prescribed tolerances are not adhered toand difiiculties arise in using swage type couplings with such conduits.

This invention contemplates a method of consistently producing properconnections between swage type cou plings and tubes which deviatesomewhat in the external dimension from prescribed tolerances.

Referring now to FIG. 2, applicant has provided a cup-shaped gaugedevice indicated generally at 32, with the depth of the generally rightcylindrical bore 34 of the cup being precisely dimensioned L-l, and thediameter of the bore being precisely dimensioned Dl. The relationshipbetween the dimensions L-l and Dl are selected in accordance with thelinear nut travel required to produce optimum swaging, and, in turn, inaccordance with the pitch of the threads 18 of the coupling and thedesign of various coacting camming surfaces on the front and backferrules and on the angular tapered mouth 22 for a particular fitting.

FIG. 3 illustrates a gauge device similar to that shown and described inFIG. 2 with corresponding elements being indicated by correspondingprimed numerals. Corresponding dimensions of the cup-type gauge of FIG.3 are demoted by D2 and L-2, which are selected in the same manner aswere L-1 and Dl described above in relation to the cap gauge of FIG. 2.The respective cap gauges are of similar design but have bores ofdifferent diameters and depths. For purposes of illustration, thedimensional relationship between the depth and diameter of therespective bores is exaggerated. It will be noted in visually comparingthe respective gauges, that both the depth and diameter of the cap gaugeof FIG. 3 are greater than corresponding dimensions of FIG. 2. Thesignificance of this dimensional relationship will be discussed in moredetail hereinafter.

In practicing the method of applicant, a cup-type gauge 32 is selectedto fit snugly over the outer surface of a tube 30. If the particulartube to be used has an outside diameter of Dl, a gauge with a borediameter of Dl is selected and inserted upon the tube until it bottomsin the lowermost part of the bore 34. With the cup gauge 32 bottomedsnugly over the tube 30, a mark is made, as by an aerosol can 38containing a marking compound 42, possibly paint, at the juncture of theupper face of the gauge and the tube 30. Scribing, or any other suitablemethod of marking may be used. The juncture of the gauge and the tube orpipe 30 is indicated by reference numeral 40.

In FIG. 5 there is shown a tube 30 having an outer diameter of D1 and amarking 42 thereon at a point 40 which is located a ditsance L-l fromthe end thereof as dictated by the depth L-l of the bore 34 of gauge 32.In selecting the proper gauge, should it have been found that the tube30 had an external diameter of D2, gauge cup 32 would have been used formarking the pipe and the juncture 40 and corresponding mark 42 wouldhave been a distance L-2 from the end of the pipe.

Referring again to FIG. 1, the tube 30 which has been marked inaccordance with the above-described procedures is inserted into thefitting 10 and abutted against shouder 17. To complete the connectionthe coupling nut 20 is advanced upon the coupling body until the face 19of the nut overlies the point 40 on the tube as illustrated in FIG. 6.As the coupling nut is rotated, the back ferrule 28 is driven againstthe tapered mouth of the front ferrule 26 and, by force transmittedthrough the back ferrule, the front ferrule is driven into the taperedmouth 22 of the body. As the ferrules are driven forwardly they arecammed radially inwardly against the external surface of the malemember, thereby swaging the latter and interlocking fitting and tube.

To produce consistently the correct: amount of swaging, the coupling nutmust be advanced a lesser amount when an oversized tube is being usedthan when an undersized tube is used. Accordingly, if the bore diameterof one gauge cap is greater than that of another gauge, the bore depthof the one gauge will also be greater than that of the other. Therefore,the proper selection and use of the various gauges will position thejuncture 40 at a greater distance from the end of the tubes as the tubesincrease in diameter, thereby to indicate less advance of the couplingnut for larger tubes.

It will be apparent that in practicing the present method the tube mustbe properly bottomed in the cap gauge. Generally the skilled user canascertain by the feel of the gauge whether or not the tube is properlybottomed. However, to avoid the necessity of relying upon the experienceand skill of the user, there may be provided a modified, or alternative,form of cap gauge 32",. as shown in FIG. 7, which permits a visualobservation of the condition of the tube with respect to the gauge.

The cap gauge 32 includes an opening or window 44 therethrough to permita visual observation of the relationship between the end of the tube andthe bottom of the cap gauge. The opening 44 is flush with the bottom ofthe bore in the cap gauge and extends longitudinally thereof a distanceto allow the user to observe easily the fit of the tube in the gauge.After the tube is properly positioned in the gauge 32" the tube may bemarked with a material 42 and assembled with a swage type fitting in themanner described hereinabove.

As a further modification of applicants method and apparatus the upperextremity 46 of the opening 44 may be positioned a distance L from thebottom of the bore. The mark or other indicia would then be placed onthe tube at the point where it intersects the face 46 of the opening. Inpracticing this latter embodiment of the invention it is preferred toplace the mark on the tube by means of a scribe or some other instrumentinstead of a coating material, such as paint. The continued use ofpaint, or equivalent material, with the cap gauge 32 of FIG. 7eventually will affect the necessary surface properties of the bore.

In the present method as described above the rear face 19 of thecoupling nut 20 is advanced until it precisely intersects, or overlies,the point marked 40 on the tube. In certain cases, however, the point 40could be placed on the tube at a distance from the end thereofcorresponding to distance L-1 plus an arbitrary but fixed distance X,for example. In the latter case the coupling nut would be advanced untilface 19 thereof is the distance X from the point 40 indicated on thetube, as measured by a gauge. Such a gauge might be a fixed gauge havinga thickness equal to X.

The invention has been illustrated above in connection with a particularfitting having a coupling nut which includes a face 19 thereon. Thisface 19 is utilized as a reference surface in the foregoingillustrations. The method of applicant could also be practiced by usingother reference surfaces that might be provided on a coupling nut.

The invention claimed is:

1. A gauging device for use in connection with the assembly of a malemember and a coupling of the type which comprises a coupling body havinga bore therein, said bore including a tapered mouth, a tapered ferrulein the tapered mouth, and a coupling nut threadedly engaging thecoupling body and in force transmitting engagement with the ferrule sothat a prescribed amount of rotation of the coupling nut upon thecoupling body will force the ferrule a given distance into the taperedmouth causing the ferrule to contract radially upon a male memberdisposed in the bore thereby to produce the desired connection with thecoupling, comprising a series of cup type gauges each having a generallyright cylindrical bore therein adapted to receive a male member, thebore of each of the cup type gauges being provided with an openingthrough the wall thereof which extends longitudinally from the bottom ofthe bore, the relationships between the depth and diameter of each borebeing selected so that the point of intersection of the bore of thegauge with a male member of substantially the size of the bore andreceived therein will indicate said prescribed amount of rotation of thecoupling nut required to produce the desired magnitude of ferrulecontraction upon said male member.

2. A gauging device for measuring the amount of radial contractionrequired to secure a male member within a coupling of the type whichcomprises a coupling body having a bore therein, said bore including atapered mouth, a tapered ferrule in the tapered mouth, and a couplingnut threadedly engaging the coupling body and in force transmittingengagement with the ferrule so that a prescribed amount of rotation ofthe coupling nut upon the coupling body will force the ferrule a givendistance into the tapered mouth causing the ferrule to contract radiallyupon a male member disposed in the bore to thereby produce the desiredconnection with the coupling, said gauging device comprising a pluralityof cup type gauges, each gauge having a generally right cylindricalblind bore therein with the bottom thereof being generally normal to thewalls of the bore, the dimensions of depth and diameter of the bore ineach cup type gauge being dictated by the depth of the bore of saidcoupling body, the degree of taper of the tapered mouth, the degree oftaper of the tapered ferrule, and the pitch of the threads between thecoupling nut and the coupling body, so that the point of intersection ofthe bore of a given cup type gauge with a given male member ofsubstantially the size of the bore and received therein will indicatethe prescribed amount of rotation of the coupling nut required toproduce the desired magnitude of ferrule contraction upon the said malemember, the dimensions of bore depth and the dimensions of bore diameterof any particular gauge being either greater or lesser than thecorresponding dimensions of any one of the other gauges of the gaugingdevice.

References Cited UNITED STATES PATENTS 1,025,255 5/1912 Driver 33-178 XFOREIGN PATENTS 1,506 3/1863 Sardinia.

SAMUEL S. MATTHEWS, Primary Examiner.

2. A GAUGING DEVICE FOR MEASURING THE AMOUNT OF RADIAL CONTRACTIONREQUIRED TO SECURE A MALE MEMBER WITHIN A COUPLING OF THE TYPE WHICHCOMPRISES A COUPLING BODY HAVING A BORE THEREIN, SAID BORE INCLUDING ATAPERED MOUTH, A TAPERED FERRULE INT THE TAPERED MOUTH, AND COUPLING NUTTHREADEDLY ENGAGING THE COUPLING BODY AND A FORCE TRANSMITTINGENGAGEMENT WITH THE FERRULE SO THAT A PRESCRIBED AMOUNT OF ROTATION OFTHE COUPLING NUT UPON THE COUPLING BODY WILL FORCE THE FERRULE A GIVENDISTANCE INTO THE TAPERED MOUTH CAUSING THE FERRULE TO CONTRACT RADIALLYUPON A MALE MEMBER DISPOSED IN THE BORE TO THEREBY PRODUCE THE DESIREDCONNECTION WITH THE COUPLING, SAID GAUGING DEVICE COMPRISING A PLURALITYOF CUP TYPE GAUGES, EACH GAUGE HAVING A GENERALLY RIGHT CYLINDRICALBLIND BORE THEREIN WITH THE BOTTOM THEREOF BEING GENERALLY NORMAL TO THEWALLS OF THE BORE, THE DIMENSIONS OF DEPTH AND DIAMETER OF THE BORE INEACH CUP TYPE GAUGE BEING DICTATED BY THE DEPTH OF THE BORE OF SAIDCOUPLING BODY, THE DEGREE OF TAPER OF THE TAPERED MOUTH, THE DEGREE OFTAPER OF THE TAPERED FERRULE, AND THE PITCH OF THE THREADS BETWEEN THECOUPLING NUT AND THE COUPLING BODY, SO THAT THE POINT OF INTERSECTION OFTHE BORE OF A GIVEN CUP TYPE GAUGE WITH A GIVEN MALE MEMBER OFSUBSTANTIALLY THE SIZE OF THE BORE AND RECEIVED THEREIN WILL INDICATETHE PRESCRIBED AMOUNT OF ROTATION OF THE COUPLING NUT REQUIRED TOPRODUCE THE DESIRED MAGNITUDE OF FERRULE CONTRACTION UPON THE SAID MALEMEMBER, THE DIMENSIONS OF BORE DEPTH AND THE DIMENSIONS OF BORE DIAMETEROF ANY PARTICULAR GAUGE BEING EITHER GREATER OR LESSER THAN THECORRESPONDING DIMENSIONS OF ANY ONE OF THE OTHER GAUGES OF THE GAUGINGDEVICE.